Although most people tolerate Vimpat well, adverse effects are possible. Some of the commonly reported side effects of Vimpat include dizziness, nausea, and vomiting. When side effects do occur, in most cases, they are minor and can easily be treated by you or your healthcare provider. Vimpat side effects insomnia VIMPAT is a prescription medicine that has been approved to treat partialonset seizures in people 4 years of age and older. It is approved to be used alone or with other medicines to treat partialonset seizures. Filmcoated tablet. Vimpat 50 mg filmcoated tablets. Could Vimpat cause Speech impairment (adult)? We studied 6, Vimpat users who have side effects from FDA and eHealthme. Among them, have Speech impairment (adult).